The cause of sarcoidosis remains elusive; however, most experts agree upon several “essential ingredients.” Strong evidence implicates genetic factors predisposing certain individuals to the development of sarcoidosis. The evolutionary factors driving these genetic characteristics are unclear, but a reasonable case could be made for the sarcoidosis genotype being protective against common human infections, including MycobacteriumTB. Many sarcoidosis patients are hyperresponsive to immunogenic TB antigens in the absence of active or latent TB infection. That said, the immune response is not TB-specific, because immune cells derived from patients with sarcoidosis produce abnormally high levels of Th1 cytokines under conditions modeling the immune response to antigens present in an array of bacteria and fungi. Thus, it is not surprising that numerous organisms (and molecules) are incriminated in the pathogenesis of sarcoidosis.